A tape guide cylinder mounted in a cassette case of various devices, such as a tape-recorder or a video cassette tape, is an important component for ensuring the constant running operation of the tape, such as recording, playing back or rewinding.
For this reason, an extremely high precision of its size is essential while at the same time a large cost reduction is necessary for mass consumption. Consequently, development and research have been positively carried out for achieving the improvement in materials.
As an example, plastics of a low cost, brass or aluminium alloy of a low cost having excellent grinding ability have been utilized for producing the tape guide cylinder, or the tape guide cylinder made of brass or aluminium alloy has been provided with a hard chrome plating at its outer circumference.
However, the plastic material is defective in durability and wear-resistance, while the brass or the aluminium alloy is also poor in durability for practical use. On the other hand, the tape guide cylinder made of brass or aluminium alloy provided a hard chrome plating at its outer surface, is high in production costs, especially the processing step for providing the hard chrome plating costs more than the cylinder itself, which does not reduce the production costs.
In view of the foregoing, there has been proposed a process for preparing the tape guide cylinder at a low cost with improved durability and wear-resistatnce, as well as for preparing the product of a light weight (Japanese Opened Patent Application No. 38778/85). However, the process needs further improvement to obtain a degree of high precision with respect to the recent technical progress.
Since such type of the tape guide cylinder is an important component for ensuring constant running operation, as stated previously, its original shape (especially its size) has strictly been maintained to avoid mis-alignment with existing devices, so that its modification has never been studied to achieve a reduction in cost.
Accordingly, an object of the invention is to reduce the production costs through a consistent process, improve the durability, the wear-resistance and the precision of the final product, as well as to achieve the weight reduction of the tape guide cylinder.